Organizations can be viewed as opportunity structures motivating strategic behavior on the part of their participants and the strategic process in organizations constitutes an internalized and contrived evolutonary mechanism nested in the external context. This argument provides a basis for integrating strategic management with organizational ecological theory. Three types of organizational change are considered: (1) Adaptation involving changes in peripheral features of organizations, (2) strategic renewal involving changes in core features generated through intra-organizational ecological processes, and (3) changes in core features mandated by top management in response to external pressures. The behavioral mechanisms involved in each of these change processes and their effect on probabilities of organizational survival are considered. There is no paradox in the view that large organizations are both more likely to manifest strategic and structural inertia and to have lower death rates.